Remove unnecessary custom signalling session

{{cookiecutter.app_name}}/{{cookiecutter.app_name}}/extensions.py

@@ -9,39 +9,8 @@ bcrypt = Bcrypt()
 from flask.ext.login import LoginManager
 login_manager = LoginManager()
 
-from flask.ext.sqlalchemy import SQLAlchemy, SignallingSession, SessionBase
+from flask.ext.sqlalchemy import SQLAlchemy
-class _SignallingSession(SignallingSession):
+db = SQLAlchemy()
-    """A subclass of `SignallingSession` that allows for `binds` to be specified
-    in the `options` keyword arguments.
-
-    """
-    def __init__(self, db, autocommit=False, autoflush=True, **options):
-        self.app = db.get_app()
-        self._model_changes = {}
-        self.emit_modification_signals = \
-            self.app.config['SQLALCHEMY_TRACK_MODIFICATIONS']
-
-        bind = options.pop('bind', None)
-        if bind is None:
-            bind = db.engine
-
-        binds = options.pop('binds', None)
-        if binds is None:
-            binds = db.get_binds(self.app)
-
-        SessionBase.__init__(self,
-                             autocommit=autocommit,
-                             autoflush=autoflush,
-                             bind=bind,
-                             binds=binds,
-                             **options)
-
-
-class _SQLAlchemy(SQLAlchemy):
-    """A subclass of `SQLAlchemy` that uses `_SignallingSession`."""
-    def create_session(self, options):
-        return _SignallingSession(self, **options)
-db = _SQLAlchemy()
 
 from flask.ext.migrate import Migrate
 migrate = Migrate()